This application, and the innovations and related subject matter disclosed herein, (collectively referred to as the “disclosure”) generally concern medical instruments configured for viewing, treating or otherwise manipulating an anatomical target site in a human or animal body. Such instruments can be configured as, for example, medical endoscope instruments and/or related systems. Principles disclosed herein can be applied to a wide variety of medical instruments (e.g., resectoscopes, laparoscopes).
Conventional endoscopes have an elongate outer sheath configured for insertion into an anatomical region normally obscured from view, treatment or other manipulation. Such an anatomical region and tissue within and/or adjacent to such a region are collectively referred to herein as “target sites” and individually referred to as a “target site.”
In some types of endoscopes, such as resectoscopes, the elongate outer sheath typically defines a distal end portion configured to house at least one device configured to view, treat and/or otherwise manipulate a target site. As used herein, “internal instrument” means a device configured to be slideably received in a sheath of an endoscope and to view, treat and/or otherwise manipulate a target site.
In many instances, an internal instrument can move longitudinally to and fro relative to the distal end portion, defining a working stroke through which the device can move. A length of an insertable portion of the elongate outer sheath, plus a length of the portion of the working stroke extending beyond the distal end of the outer sheath can define a maximum insertion length of an endoscope.
Some outer sheaths house two or more internal instruments. For example, U.S. Pat. No. 5,287,845, which is hereby incorporated by reference in its entirety, describes an endoscope for transurethral surgery having a main body non-rotatably supporting an optical system and a surgical instrument (e.g., scissors, tongs or, typically, a high-frequency cutting electrode). An outer tube affixed to the main body tubularly encloses the optical system and the surgical instrument. The outer tube of U.S. Pat. No. 5,287,845 is rotatably mounted relative to the main body, the optical system and the surgical instrument.
When using such a conventional endoscope, visibility of the target site (sometimes also referred to as an “operative field”) can be obscured by a turbid fluid. For example, in a medical environment, blood or another bodily fluid can obscure visibility. To address such poor visibility, some endoscopes have been configured to continuously inject a working fluid into the target site in an attempt to dilute the turbid fluid and improve visibility. For example, U.S. Pat. No. 3,835,842, which hereby incorporated by reference in its entirety, discloses an endoscope configured to supply a continuous inflow of clear irrigating fluid to an operative field and to continuously drain turbid fluid from the operative field.
Conventional endoscopes that provide continuous irrigation suffer from several disadvantages. For example, some conventional endoscopes do not provide a rotational coupling between an external surface in contact with the patient and the device configured to view, treat and/or manipulate the treatment site. In these embodiments, multiple removals and insertions may be necessary to reorient the device. Other conventional endoscopes combine continuous irrigation with a rotatable outer surface, but at the expense of higher outer diameters, which might impart more trauma than a smaller outer diameter would. Previous attempts at shrinking outer dimensions of endoscopes have met with limited success since internal instruments have a finite size.
Some conventional endoscope sheaths are perforated and define a plurality of openings extending through a wall of the outer sheath and being disposed adjacent the distal end of the sheath. Such perforations can allow a turbid fluid to flow from the treatment site into a channel within the outer sheath. The fluid may then be withdrawn through the endoscope. Although such perforations can improve fluid flow from the treatment site, they might also abrade the patient's tissue, causing more trauma to the tissue than a similarly-sized, continuous outer surface without perforations.
Some previously proposed endoscopes have incorporated a separate and distinct ceramic tip component to thermally and/or electrically insulate a distal tip of an outer sheath, an inner sheath, or both. Insulating the inner or outer sheath from internal instruments (e.g., an electrode) reduces the likelihood of unintended portions of the instrument being subjected to electrical and/or thermal effects, which may damage the instruments and cause user/patient hazards.
Such tips have been attached to an outer sheath using an adhesive material, a mechanical fastener (e.g., a dimple on the tube's wall), or both. Ordinarily, a groove or other feature has been formed in the ceramic (e.g., by grinding) to accommodate such a mechanical fastener.
Improvements to conventional endoscopes have been difficult to achieve and various approaches have met with limited success, at least in part, because individual components (e.g., electrodes, telescopes) have been standardized and are widely available commercially. Accordingly, designers tend to use previously available components in an attempt to keep costs at reasonable levels, which in turn limits the extent of possible improvements.
In addition, there are many competing requirements that a designer must attempt to satisfy. For example, to reduce patient trauma, an outer diameter of an endoscope sheath is desirably as small as possible. Nonetheless, to obtain useful performance from internal instruments (e.g., well-resolved images from visualization instruments, such as, for example, an optical telescope) received within the outer sheath, an interior dimension is desirably as large as possible to provide sufficient maneuverability of internal instruments and/or sufficiently open channels for fluid inflow and outflow. In addition, larger internal dimensions can allow higher performance internal instruments to be used. Thus, improving performance in one area has typically resulted in little to no, and sometimes negative, performance gains in other areas. Despite the many configurations that have been proposed, a need remains for endoscopes that reduce the risk of patient trauma. For example, there is a need for endoscopes having a smaller outer diameter. A need also exists for endoscopes with longer working strokes. High-quality imaging devices for endoscopes are also needed. Endoscopes with improved inflow and outflow rates are also needed. In addition, a need exists for improved insulation between internal instruments and the distal tip of the endoscope. And, there remains the need for low-cost and economical endoscopes.